feat(intel): add SMC support for HWMON voltage and temp sensor

Add support to read temperature and voltage using SMC command

Signed-off-by: Kris Chaplin <kris.chaplin@linux.intel.com>
Signed-off-by: Jit Loon Lim <jit.loon.lim@intel.com>
Change-Id: I806611610043906b720b5096728a5deb5d652b1d
diff --git a/plat/intel/soc/common/include/socfpga_mailbox.h b/plat/intel/soc/common/include/socfpga_mailbox.h
index 09dd117..b260a62 100644
--- a/plat/intel/soc/common/include/socfpga_mailbox.h
+++ b/plat/intel/soc/common/include/socfpga_mailbox.h
@@ -51,6 +51,11 @@
 #define MBOX_RECONFIG_DATA		0x08
 #define MBOX_RECONFIG_STATUS		0x09
 
+/* HWMON Commands */
+#define MBOX_HWMON_READVOLT		0x18
+#define MBOX_HWMON_READTEMP		0x19
+
+
 /* QSPI Commands */
 #define MBOX_CMD_QSPI_OPEN		0x32
 #define MBOX_CMD_QSPI_CLOSE		0x33
@@ -178,5 +183,7 @@
 int mailbox_rsu_status(uint32_t *resp_buf, uint32_t resp_buf_len);
 int mailbox_rsu_update(uint32_t *flash_offset);
 int mailbox_hps_stage_notify(uint32_t execution_stage);
+int mailbox_hwmon_readtemp(uint32_t chan, uint32_t *resp_buf);
+int mailbox_hwmon_readvolt(uint32_t chan, uint32_t *resp_buf);
 
 #endif /* SOCFPGA_MBOX_H */